Surveillance system, method, computer program, storage medium and surveillance device

ABSTRACT

A surveillance system having an interface to a camera network for video surveillance of a surveillance area. The camera network includes a plurality of cameras each for capturing a surveillance subarea. The cameras are designed to provide surveillance images of the surveillance subareas. The surveillance system also includes a surveillance device for re-identifying people in the surveillance images. The surveillance device includes a person detection module for detecting people and an object detection module 10 for detecting objects. The surveillance device 5 includes an assignment module 12 designed to assign at least one item of object information to a person 4, and an action detection module 11 designed to detect an action of the person 4 on one of the objects 8.

BACKGROUND OF THE INVENTION

The invention relates to a surveillance system. The invention alsorelates to a method, a computer program, a storage medium and asurveillance device.

Video-based surveillance and services are a key aspect in many retailapplications, for instance visitor-flow analysis, anti-theft andanti-vandalism protection, etc. Modern camera systems also allowanalysis of visitor traffic, for instance in order to optimize thedeployment of personnel or to evaluate the impact of marketingactivities. Often this also involves tracking individual peoplethroughout the camera network, which requires re-identifying a person indifferent cameras. Identifying people can usually prove difficultbecause standard techniques for person re-identification can often beerror-prone, or a person can look different in different cameras.

Document DE 102008001126 A1, which arguably constitutes the closestprior art, discloses an inventory module for a video surveillancesystem, which video surveillance system comprises at least onesurveillance camera which is directed and/or can be directed onto asurveillance area, in particular onto a storage and/or retail area,containing products, and has a detection device designed to detect theproducts, which detection involves obtaining an item of positioninformation and an item of identification information for the detectedproduct, and comprises an assignment device, which is designed to modela spatial distribution of the products in the surveillance area by meansof the position information and the identification information from aplurality of detected products. In addition, the inventory modulecomprises an object detection device for detecting moving objects, inparticular shoppers, and comprises a correlation device designed tocorrelate the movement behavior of the moving objects with thearrangement of the products.

SUMMARY OF THE INVENTION

The subject of the invention is a surveillance system. The surveillancesystem comprises an interface to a camera network, or alternativelycomprises the camera network, which is designed and/or is suitable forvideo surveillance of the surveillance area. The surveillance system canbe distributed over a plurality of segments of the surveillance areaand/or over additional areas, for instance of a central securitysurveillance system. The surveillance area can include an indoor and/oroutdoor area. For example, the surveillance area is a public area, forinstance a department store, a station, an airport or suchlike.

The camera network comprises a plurality of cameras, each designedand/or suitable for capturing a surveillance subarea of the surveillancearea. The cameras can be color, monochrome and/or infrared cameras. Thecameras are preferably located in the surveillance area. Thesurveillance subareas under surveillance by different cameras canoverlap one another. Alternatively, the surveillance subareas ofdifferent cameras do not overlap. The cameras are designed to providesurveillance images of the surveillance subareas, in particular as videodata.

The surveillance system comprises a surveillance device that is designedand/or suitable for re-identifying people in the surveillance images.The person re-identification can be used to re-identify a definableperson to be found, and/or a plurality of people, in differentsurveillance images. The people to be re-identified may be individualpeople, groups of people, or even animals and/or objects. In particular,the surveillance device is provided with a plurality of surveillanceimages from different cameras. For example, the cameras and thesurveillance device each have an interface, which interfaces can beinterconnected for data transfer.

The surveillance device comprises a person detection module that isdesigned and/or suitable for detecting people in the surveillanceimages. For example, the surveillance device is in the form of acomputer device, and the person detection module can be in the form of ahardware or software module of the surveillance device. In particular,the person detection module is designed to analyze and/or process thesurveillance images. At least, or precisely, one person can be containedor be present in the surveillance images, in particular temporarily orpermanently. The person detection module is designed to detectautomatically on the basis of the surveillance images a person, somepeople and/or all the people in the surveillance images. The persondetection module is designed in particular to examine the surveillanceimages on the basis of rules, for instance on the basis of specifiedparameters and/or characteristics, which parameters are designed to findpeople and/or to distinguish people from background. Alternatively,however, a user can also manually pick out individual people and/or allthe people in the surveillance images.

The surveillance device comprises an object detection module that isdesigned and/or suitable for detecting objects in the surveillanceimages. For example, the object detection module can be in the form ofan additional hardware or software module of the surveillance device.Said detection of the object involves the object detection moduleobtaining object information for the detected object. In particular, theobject detection module is designed to perform image analysis and/orprocessing, preferably on the basis of digital or analog imageprocessing algorithms, on the objects in the surveillance images inorder to obtain the object information. In particular, the objects aredetected, for example, by computing feature descriptors of the objects,and comparing with reference feature descriptors. In principle, theobjects can be of any form, although in particular in the present case,the objects in the surveillance area are retail products. Alternatively,however, the objects can also be other products such as tools,consumables, pharmaceutical products or other stock in a storage area.Alternatively, the object may also be a returnable article, however, forinstance bottles, packaging, etc. The objects are preferably positionedin a regular manner in storage structures such as shelves or the like.The surveillance area is preferably a storage and/or retail area, inparticular a sales floor, for instance of a supermarket.

The surveillance device comprises an assignment module that is designedand/or suitable for assigning at least one item of object information toa person. For example, the assignment module can be in the form of anadditional hardware or software module of the surveillance device. Inparticular, the assignment module is designed to assign a specific itemof object information to precisely one person in the surveillanceimages. This person-specific object information preferably is assignedand/or can be assigned permanently and/or uniquely and/or fixedly to theprecisely one person. The assignment module is designed to provide thesurveillance images containing the detected person to whom is assignedat least, or precisely, the one item of object information.

The invention also proposes that the surveillance device comprises anaction detection module that is designed and/or suitable for detectingan action of the person on one of the objects. For example, the actiondetection module can be in the form of an additional hardware orsoftware module of the surveillance device. In particular, the actiondetection module is designed to analyze and/or evaluate movements and/oractivities of the person in the surveillance images in order to detectan action being performed by the person on the object. Specifically, theaction detection module is designed to use methods from the field of“action recognition” to detect the actions. The assignment module isdesigned to assign the at least one item of object information for anobject to the person if at least one action condition is satisfied foran action on the object. In particular, the object information isassigned if the object detection module detects the object, and theaction detection module at the same time and/or in the same image regiondetects on the object an action of the detected person that results inthe action condition being satisfied. For example, the action conditionmay be a defined action of the person on the object and/or a change inthe object information resulting from the action. The assigned objectinformation is preferably used for the re-identification of the personin different surveillance subareas. Alternatively, or optionallyadditionally, however, the object information assigned to the person canalso be used for the surveillance of an object distribution in thesurveillance area. For example, the object information can be providedto an inventory module for this purpose.

Thus the advantage of the invention is that the action detection modulecan significantly improve surveillance and/or re-identification ofpeople in the surveillance area. The assigning of object informationallows the people to be provided with additional identificationfeatures, and therefore not only can the features of the actual personbe used, but also the object information assigned to the individualperson can be employed in and/or for the re-identification of thepeople. Therefore the invention is based on the consideration offacilitating improved re-identification of people in a surveillancearea.

In a further embodiment, the surveillance device comprises a comparisonmodule which is designed and/or suitable for comparing objectinformation that is assigned to the person and is from a plurality ofdifferent, in particular at least two different, surveillance subareas.For example, the comparison module can be in the form of an additionalhardware or software module of the surveillance device. The comparisonmodule is designed to re-identify a person in the surveillance images inthe event of a match for the object information from at least twosurveillance subareas. For this purpose, the comparison module accessesin particular the person-specific object information, which is providedby the assignment module, in order to take into account the associatedobject information in comparing the people detected in the plurality ofsurveillance subareas. If a match exists, or a minimum match exists,then the person can be considered re-identified. Thus instead ofsearching in the images just for the person being sought, it is possibleto use, for example, a match for the associated object information asevidence and/or an indication of the person to be re-identified.

According to a specific embodiment, the assignment module is designed toassign to a plurality of people different object information from one ormore surveillance subareas. In particular, each person is assigned atleast, or precisely, one item of person-specific object information fromwhich the person can be re-identified. The comparison module is designedto compare the people on the basis of the assigned object information,wherein a person is re-identified in the event of a match for theassigned object information. In particular, a person is deemedre-identified in the surveillance images in the event of a match for atleast one item, some or all of the object information assigned to theperson. Preferably, the person re-identification is used to track and/orfollow a person in the surveillance area and/or in one or moresurveillance subareas. The tracked and/or followed person can bere-identified as precisely one person if the associated objectinformation acquired in the different surveillance subareas matchesand/or is identical. Thus the object of the invention is to use theobject information assigned to the person in order to re-identify theperson.

In a further embodiment, the action condition comprises an action on theobject that results in the object accompanying the person across atleast two different surveillance subareas. In particular, the actioncondition is satisfied if the person to be re-identified has been in thevicinity of the object for a prolonged period and/or performs anoperation on the object and/or moves with the object. For example, theaction condition is satisfied if the person takes an article from ashelf and/or places the article in an accompanying shopping trolley orbasket or suchlike. Thus the object information assigned to the personis based in particular on an object that can be re-identified and isuniquely assigned to the person, and that accompanies the person acrossa plurality of surveillance subareas.

According to a further specific embodiment, the object informationcomprises at least, or precisely, one position feature of the object.The object detection module is designed in particular to locate theobject in the surveillance images on the basis of the position feature.For example, the object detection module can detect a position and/or achange in position of the object in the surveillance area on the basisof the position feature. Alternatively, or optionally additionally, theobject information comprises at least, or precisely, one identificationfeature of the object. The object detection module is designed inparticular to identify the object in the surveillance images on thebasis of the identification feature. For example, the identificationfeature describes a size and/or shape and/or color and/or type, forinstance food, clothing, etc., of the object. Thus a surveillance deviceis proposed that is characterized by particularly reliableidentification of identical or different objects in differentsurveillance subareas.

In a further embodiment, the assignment module is designed to assign toa person a plurality of items of object information from differentsurveillance subareas according to the action using the correspondingobjects. The action detection module is designed in particular to assignto the person, whenever the person performs on an object an action thatsatisfies the action condition, an additional associated item of objectinformation for the corresponding object. A person can preferably beassigned any number of items of object information according to theactions, on the basis of which the person can be uniquely identifiedand/or can be distinguished from other people. For example, a person canthus be assigned a multiplicity of items of object information over theperiod of time spent in the surveillance area, making it significantlyeasier to re-identify the person in the different surveillance subareas.

According to a development, the person detection module is designed toacquire at least, or precisely, one item of person information for thedetected persons. The surveillance device is designed in particular toidentify and/or re-identify the person on the basis of the assignedobject information and the person information. The person informationcomprises in particular a person-specific feature or a feature linked tothe person, specifically at least, or precisely, one abstractperson-feature of the detected person. The person detection module ispreferably designed to extract the person information for the detectedperson from the surveillance images. The person detection module isdesigned to provide, in particular to the comparison module, the personinformation for the purpose of re-identifying the person. In particular,the comparison module can analyze and/or evaluate the person informationin addition to the object information.

The object information preferably has a higher priority than the personinformation, wherein in the event of a match for the person information,and in the event of a discrepancy in the object information, the personis not re-identified or only partially re-identified. A surveillancedevice is thus proposed that is characterized by particularly reliablere-identification of people in different surveillance subareas.

In a further specific implementation, the person information comprisesan appearance feature and/or a clothing feature and/or a motion featureof the person. In particular, the at least one appearance featuredescribes a gender, hair color, skin color, facial features, height,build, etc. of the person. In particular, the at least one clothingfeature describes a clothing color, type of clothing, etc. of theperson. In particular, the motion feature describes a gait, speed ofmovement, direction of movement, etc. of the person.

A method for re-identifying people in surveillance images forms afurther subject of the invention. In said method, people are detected inthe surveillance images. For example, the surveillance images arecaptured by a camera network comprising a plurality of cameras,preferably at least, or precisely, two cameras. In a further step,objects are detected in the surveillance images, which detection of theobjects involves obtaining object information for the detected object.In particular, the object information is acquired from objects arrangedin the surveillance area in a regular manner. In a further step, anaction of the person on an object is detected, and in the event of anaction condition being satisfied, object information for the object isassigned to the person for the purpose re-identification. In particular,the object information is assigned to the person permanently or at leastfor the length of time the person spends in the surveillance area.Particularly preferably, the person can be assigned a plurality of itemsof object information for identical, different or similar objects if theaction condition is satisfied for an action with the respective objects.

The assigned object information from a plurality of differentsurveillance subareas is preferably compared, and in the event of amatch for the assigned object information from at least two differentsurveillance subareas, a person is re-identified in some or all of thesurveillance images. In particular for this purpose, the assigned objectinformation is acquired in at least, or precisely, two, preferably inall, surveillance subareas of the surveillance area. In particular, aperson detected in the surveillance images is re-identified if theassociated object information at least from a first surveillance subareamatches the associated object information from a second surveillancesubarea.

In a further method step, one or more items of person information for aperson, for instance specific person features of the detected person,can be extracted from the surveillance images and provided forre-identification of the person. In particular, the person informationcan be used in addition to the object information for the personre-identification in order to identify and/or re-identify the person inthe surveillance images.

The method is preferably designed to track the person in thesurveillance images on the basis of a match for the object informationand/or the person information from at least two different surveillancesubareas. The person in the surveillance images is preferablyre-identified if at least one item of associated object information fromat least two different surveillance subareas matches. In particular, thepeople are detected automatically in the surveillance images andfollowed and/or tracked over time. A person can hence be tracked andidentified uniquely and seamlessly across the entire camera network.

A computer program forms a further subject of the invention, whichcomputer program is designed to perform the method for re-identifyingpeople when the computer program is executed on a computer, a processorunit or the surveillance device.

A storage medium forms a further subject of the invention, which storagemedium comprises the computer program as described above.

A surveillance device already described above for re-identifying peoplein surveillance images forms a further subject of the invention, whichsurveillance device is preferably designed to perform the describedmethod.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages, effects and embodiments appear in the accompanyingfigures and the description thereof, in which figures:

FIG. 1 shows a schematic diagram of a surveillance system comprising asurveillance device as an exemplary embodiment of the invention;

FIG. 2 shows a schematic block diagram of the surveillance system fromFIG. 1;

FIG. 3 shows a schematic diagram of method steps of a method.

DETAILED DESCRIPTION

In a highly schematic representation, FIG. 1 shows a surveillance system1 that is used for surveillance of a surveillance area 2. Thesurveillance system 1 comprises a camera network 3, which is designedfor video surveillance of the surveillance area 2. The camera network 3comprises for this purpose a plurality of cameras 3 a, b, for example inthe form of video cameras, preferably color cameras. The surveillancearea 2 is formed by a sales floor, for example, and the cameras 3 a, bcan be installed at different positions in order to provide surveillanceof different surveillance subareas 2 a, b of the surveillance area 2.

The surveillance area 2 contains people 4 who can move freely there. Thecameras 3 a, b are likewise used for video surveillance of the people 4.The cameras 3 a, b depict the respective surveillance subareas 2 a, b inthe form of surveillance images 6 a, b, with the cameras 3 a, bproviding the surveillance images 6 a, b as video sequences.

The surveillance system 1 comprises a surveillance device 5 which isdesigned to analyze and/or process the surveillance images 6 a, b fromthe cameras 3 a, b. For this purpose, the cameras 3 a, b can beconnected wirelessly or by means of cables to the surveillance device 5.The surveillance images 6 a, b captured by the cameras 3 a, b are thusrouted to the surveillance device 5, where they are processed.

Located in the surveillance area 2 is a storage structure 7, forinstance a plurality of shelves, in which are ranged objects 8, forexample a variety of products. In particular, the objects 8 are articlesthat are for sale and sorted in an orderly manner in the storagestructure 7.

The re-identification of people 4 plays an important role in videosurveillance of sales floors or suchlike. Since the cameras 6 a, b usedin this context generally have to cover a large area, the resolution ofan individual person 4 is low and it is not possible to use facialrecognition techniques. In addition, the large variation in a person 4in different cameras 6 a, b, for instance as a result of lightingdifferences, different views and camera angles, etc., makes it harder tore-identify the person 4 in the surveillance images 6 a, b. Algorithmsfrom the field of artificial intelligence are known whosere-identification performance is improved over the number of trainingexamples. Data protection regulations, however, make it difficult orpractically impossible to obtain a sufficient amount of data.

It is therefore proposed to expand the current methods forappearance-based person re-identification by employing domain knowledge.This is done by integrating directly into the analysis methods theparticular circumstances in specialized stores, for instance asupermarket, hardware store, clothing store, shoe shops, textilesuppliers, motor-component store, etc., instead of being restricted toinvestigating the appearance of each individual person 4.

The surveillance device 5 is designed to re-identify people 4 in thesurveillance images 6 a, b from the plurality of cameras 3 a, b on thebasis of object information assigned to the person 4. Whereaspresent-day algorithms consider each person 4 per se, this approachwidens to include the objects 8 and actions in the surveillance area 2that are linked to a person 4. The surveillance device 5 is designed inthis case to detect the objects 8 in the surveillance images 6 a, b andto obtain an associated item of information for each of the objects 8.

The further processing of the surveillance images 6 a, b and of theobject information is explained with reference to FIG. 2, which shows aschematic block diagram of the surveillance system 1 as an exemplaryembodiment of the invention.

The surveillance images 6 a, b are routed from the cameras 3 a, b intothe surveillance device 5, where they are transferred to a persondetection module 9. The person detection module 9 is designed, interalia, to examine the surveillance images 6 a, b for people 4, and torecognize detected people as such. For example, the person detectionmodule 9 can analyze the surveillance images 6 a, b for certaincharacteristics, and assess on the basis of a set of rules whethersomething is a person 4 or a thing. Alternatively or additionally,however, a user can also pick out the people 4 manually in thesurveillance images 6 a, b.

The surveillance device 5 comprises an object detection module 10, whichobject detection module 10 is likewise provided with the surveillanceimages 6 a, b. For example, the object detection module 10 can usedigital image processing algorithms, in particular video contentanalysis, to detect the objects 8 in the surveillance images 6 a, b.Said detection of the objects 8 also involves obtaining objectinformation, which object information can comprise a position featureand/or an identification feature of the object 8. The object detectionmodule 10 is designed to determine a position of the associated object 8in the surveillance area 2 on the basis of the position feature, and/orto identify the object 8 on the basis of the identification feature.

In addition, the surveillance device 5 comprises an action detectionmodule 11, which action detection module 11 is designed to detect anaction of the detected person 4 in the surveillance area 2. The actiondetection module 11 is used in particular to detect an action of theperson 4 on the objects 8. For example, the action detection module 11can use known methods from the field of “action recognition” to detectthe actions performed by the person 4.

The surveillance device 5 comprises an assignment module 12 that is indata communication with the object detection module 10 and with theaction detection module 11. Stored in the assignment module 12 is atleast one action condition for the actions performed by the people 4,and the assignment module 12 is designed to assign an item ofidentification information to the person if the action condition issatisfied. In particular, the identification information is defined bythe object information for the object 8. The action condition isdefined, for example, by an action of the person 4 that results in theobject 8 permanently and/or mostly accompanying said person in a definedarea surrounding the person 4. Thus the object information can beunderstood to mean information that can be uniquely assigned to anobject 8 linked to the person 4.

The action condition can be satisfied if the person 4 takes out of thestorage structure 7 an object 8, for instance an article, thataccompanies the person from the first into the second surveillancesubarea 2 a, b. Since the position of the object 8 in the surveillanceregion 2 is known, the selected and accompanying object 8 can also bedetected and assigned to the person 4 as identification information. Forexample, a classification algorithm based on deep-learning methods canbe used for this purpose. In particular, any number of items ofidentification information can be assigned to the person 4 over theentire period of time spent in the surveillance area 2. During shopping,for instance, more and more identification information is graduallyadded to the person 4.

The assigned identification information, in particular objectinformation, is then provided to a comparison module 13 together withthe surveillance images. The person detection module 9 can also bedesigned to extract one or more items of person information for thepeople 4, and to provide this information to the comparison module 13 asadditional identification information. The comparison module 13 isdesigned to compare the identification information from the surveillanceimages 6 a, b from the first and second surveillance subareas 2 a, b,and in the event of a match for the identification information, a person4 in different surveillance images 6 a, b is re-identified as the sameperson.

Thus an improved re-identification of people 4 is proposed that takesinto account extra information beyond the appearance-basedre-identification. This approach offers a distinct advantage over baredata collection, because the re-identification of people 4 can beimproved significantly by the addition of extra identificationinformation.

Example scenarios are used below to describe the acquisition and use ofdifferent identification information. In a possible exemplaryembodiment, a person 4, for instance a customer, selects one or moreobjects 8 from the storage structure 7, wherein the action detectionmodule 11 detects an action on the object, and the assignment module 12assigns the associated object information to the person 4 on the actioncondition being satisfied.

For example, the person 4 can be assigned an item of identificationinformation if the person 4 places food, for instance fruit, milkcartons, etc. in a shopping trolley. In this case, the person 4 can bere-identified at the checkout on the basis of the accompanying foods,wherein the objects 8 placed on the belt are detected on the basis ofthe associated object information as the various foods that werepreviously put in the shopping trolley.

Alternatively, the identification information, or optionally anadditional item of identification information, can be assigned to theperson 4 if the person 4 at a self-service counter, such as those foundin bakers or self-service bakeries, personally finds and takes out thearticles. Since it is rare or forbidden for the objects 8 to be putback, the object information for the removed articles can also be usedat the checkout for re-identification.

Alternatively, the identification information, or optionally anadditional item of identification information, can be assigned to theperson 4 if the person 4 hands over a returnable item and receives avoucher in return. At the checkout, the person 4 hands over thisvoucher, and this information can be used as an additional input for there-identification.

Alternatively, the identification information, or optionally anadditional item of identification information, can be assigned to theperson 4 if the person 4 is located and/or spends a prolonged periodinside or outside a restricted-access zone, for instance a checkout areaor an area behind a counter, of the surveillance area 2. For example,only employees have access to this zone, and therefore it is possible todistinguish unambiguously between customers and employees. Thisidentification information can be used, for example, as additionalfeatures for the re-identification. In addition, employees located inthe restricted-access zones could be removed automatically from thesurveillance images 6 a, b in order to increase employee dataprotection.

Alternatively, the identification information, or optionally anadditional item of identification information, can be assigned to theperson 4 if the person 4 selects an object 8 having a clearlydistinguishable and/or unique item of object information, for instancean article of distinctive dimensions, colors and/or low demand. If theperson 4 takes a cement sack, for instance, from the storage structure7, after scanning the article at the checkout it is known immediatelythat the person is highly likely the person 4 who passed through thebuilding department and not the person 4 who passed only through theplumbing department. It is hence possible to reduce significantlyambiguities for different people 4.

FIG. 3 shows in a schematic diagram a method sequence for a method forre-identifying people 4 in the surveillance images 6 a, b. In a firstmethod step V1, a person 4 to be re-identified is selected in thesurveillance images 6 a, b. The selection can be performed hereautomatically, for instance using a trained detector, or manually by theuser during simultaneous recording of the video material. To facilitatean efficient search, it is additionally possible to save as metadataalso the results computed in the video analysis.

In a second method step V2, the actions that the person 4 performs inthe store are detected and compared with a stored action condition.Methods from the field of “action recognition” can be used to detect theactions, for example. The action condition is satisfied, for instance,if the person 4 takes an object 8 which accompanies the person over aprolonged period.

On the action condition being satisfied, the person 4 is assigned, in athird method step V3, a corresponding item of information for theaccompanying object 8, on the basis of which the person 4 can bere-identified. Depending on the number of accompanying objects 8, moreand more identification information can thus be added gradually to theperson 4, making re-identification increasingly easy.

In a fourth method step V4, the surveillance images 6 a, b are comparedwith one another, and a person 4 is re-identified in the surveillanceimages 6 a, b if the identification information assigned to the person 4matches. Instead of taking account of only the person information, forinstance green fabric (trousers) below and blue fabric (shirt) on top,the accompanying objects 8 are additionally identified on the basis ofthe object information.

1. A surveillance system (1), comprising an interface to a cameranetwork (3) for video surveillance of a surveillance area (2), whereinthe camera network (3) comprises a plurality of cameras (3 a, b), eachfor capturing a surveillance subarea (2 a, b) of the surveillance area(2), wherein the plurality of cameras (3 a, b) are designed to providesurveillance images (6 a, b) of the surveillance subareas (2 a, b),comprising a surveillance device (5) for re-identifying people (4) inthe surveillance images (6 a, b), wherein the surveillance device (5)comprises a person detection module (9), which person detection module(9) is designed to detect people (4) in the surveillance images (6 a,b), wherein the surveillance device (5) comprises an object detectionmodule (10), which object detection module (10) is designed to detectobjects (8) in the surveillance images (6 a, b), which detectioninvolves obtaining object information for the detected object (8),wherein the surveillance device (5) comprises an assignment module (12),which assignment module (12) is designed to assign at least one item ofobject information to a person (4), wherein the surveillance device (5)comprises an action detection module (11), wherein the action detectionmodule (11) is designed to detect an action of the person (4) on one ofthe objects (8), wherein the assignment module (12) is designed toassign object information for the object (8) to the person (4) for thepurpose of re-identification if at least one action condition issatisfied.
 2. The surveillance system (1) according to claim 1, whereinthe surveillance device (5) comprises a comparison module (13), whereinthe comparison module (13) is designed to compare the assigned objectinformation from a plurality of different surveillance subareas (2 a,b), wherein a person (4) is re-identified in the surveillance images (6a, b) in the event of a match for the assigned object information fromat least two surveillance subareas (2 a, b).
 3. The surveillance system(1) according to claim 2, wherein the assignment module (12) is designedto assign to a plurality of people (4) different object information fromone or more surveillance subareas (2 a, b), wherein the comparisonmodule (13) is designed to compare the people (4) on the basis of theassigned object information, wherein a person (4) is re-identified asthe same person in the event of a match for the assigned objectinformation.
 4. The surveillance system (1) according to claim 1,wherein the action condition comprises an action of the person (4) onthe object (8) that results in the object (8) accompanying the person(4) across at least two different surveillance subareas (2 a, b).
 5. Thesurveillance system (1) according to claim 1, wherein the objectinformation comprises at least one position feature and/oridentification feature of the object (8).
 6. The surveillance system (1)according to claim 1, wherein the assignment module (12) is designed toassign to precisely one person (4) a plurality of items of objectinformation from different surveillance subareas (2 a, b).
 7. Thesurveillance system (1) according to claim 1, wherein the persondetection module (9) is designed to extract at least one item of personinformation for a person (4) from the surveillance images (6 a, b), andto provide the person information for the purpose of re-identifying theperson.
 8. The surveillance system (1) according to claim 6, wherein theperson information comprises an appearance feature and/or a clothingfeature and/or a motion feature of the person.
 9. A method forre-identifying people (4) in a plurality of surveillance images (6 a,b), in which method: people (4) are detected in the surveillance images(6 a, b); objects (8) are detected in the surveillance images (6 a, b),which detection of the objects (8) involves obtaining object informationfor the detected objects; an action of the person (4) on one of theobjects (8) is detected, and in the event of at least one actioncondition being satisfied, object information for the object (8) isassigned to the person (4) for the purpose re-identification.
 10. Themethod according to claim 9, wherein the assigned object informationfrom a plurality of different surveillance subareas (2 a, b) iscompared, and in the event of a match for the assigned objectinformation from at least two different surveillance subareas (2 a, b),a person (4) is re-identified in the surveillance images (6 a, b). 11.The method according to claim 9, wherein at least one item of personinformation for a person (4) is extracted from the surveillance images(6 a, b), which person information is provided for re-identification ofthe person (4).
 12. The method according to claim 9, wherein the person(4) is tracked in the surveillance images (6 a, b) on the basis of amatch for the object information and/or the person information from atleast two different surveillance subareas (2 a, b).
 13. A computerprogram, which computer program is designed to perform all the steps ofthe method according to claim 9 when the computer program is executed ona processor unit or the surveillance device (5).
 14. A machine-readablestorage medium, in which storage medium is stored the computer programaccording to claim
 13. 15. A surveillance device (5) for re-identifyingpeople (4) in surveillance images (6 a, b), which surveillance device isconfigured to perform the method according to claim 9, wherein thesurveillance device (5) comprises a person detection module (9), whichperson detection module (9) is designed to detect people (4) in thesurveillance images (6 a, b). wherein the surveillance device (5)comprises an object detection module (10), which object detection module(10) is designed to detect objects (8) in the surveillance images (6 a,b), which detection involves obtaining object information for thedetected object (8), wherein the surveillance device (5) comprises anassignment module (12), which assignment module (12) is designed toassign at least one item of object information to a person (4), whereinthe surveillance device (5) comprises an action detection module (11),wherein the action detection module (11) is designed to detect an actionof the person (4) on one of the objects (8), wherein the assignmentmodule (12) is designed to assign object information for the object (8)to the person (4) for the purpose of re-identification if at least oneaction condition is satisfied.